Compact electronic devices that comprise a display module and an electronics module in a common housing are well known to the public. Such devices are used, for example, as portable tablet computers or as wall-mounted flight attendant panels in aircraft. In principle, these electronic devices are compact versions of a regular computer, wherein all electronics (the electronics module) of the computer, a display or display module and an input means in form of a touch-sensitive display are assembled in a single common housing.
An exemplary embodiment of an electronic device of the prior art will now be described with reference to FIGS. 1 and 2 which show a prior art device of the above type.
An electronic device 1 shown in FIGS. 1 and 2 comprises an electronics module 3 and a display module 5 that are arranged in a common housing 7. The common housing 7 is completed by a front cover or wall 9 that is attached to the common housing 7 which is formed by a back cover or wall 11 and sidewalls and frequently serves as an electromagnetic interference shielding of and for the electronic means in the electronic device 1. Said front cover 9 comprises an optional protective layer 13 and a touch-sensitive layer 15 and is used as a user input means. If the electronic device 1 comprises the optional protective layer 13 the touch-sensitive layer 15 is arranged directly adjacent to or in contact with the protective layer 13. Various kinds of touch-sensitive layers 15 are known in the prior art that can be used in electronic device 1 e.g. resistive or capacitive touch-sensitive layers 15. The protective layer 13 is frequently made from mineral or non-mineral glass. However, the protective layer 13 could also be in the form of a thin plastic foil.
Directly adjacent to the front cover 9 the display module 5 is arranged. The display module 5 comprises a liquid crystal display (LCD) layer 17 and a backlight layer 19 that are housed in a display housing 21. At least a portion of the display housing 21 and, in particular, at least the portion facing the electronics module 3 is made from a conductive material such that it provides a shielding of electromagnetic interference between the display module 5 and the electronics module 3. A transparent side or wall 23 of the display housing 21 is arranged directly adjacent to the touch-sensitive layer 15 of the front cover 9. The LCD layer 17 is arranged in contact with the transparent wall 23 of the display housing 21 and illuminated by the backlight module 19, which is arranged directly adjacent to the LCD layer 17. The display housing 21 further comprises mounting holes 25 that are used to mount the display module 5 on the electronics module 3. Instead of the mounting holes 25 other mounting means may be provided on the display housing 21.
The electronics module 3 is arranged in the common housing 7 between the back cover or wall 11 of the housing 7 and the display module 5. The electronics module 5 comprises a multi-layer printed circuit board 27. The printed circuit board has multiple layers 29, 31, 33 out of which three are shown schematically in FIG. 2. The printed circuit board 27 is delimited by a first layer 29 and a second layer 33, i.e. the first layer 29 forms one of the two extended outer surfaces of the printed circuit board 27, and the second layer 33 forms the other, opposite extended surface. The first layer 29 faces towards the display module 5 and the second layer 33 faces towards the back cover 11 of the housing 7. On the first layer 29 various electronic components are arranged such as e.g. a processor and a graphics controller.
The electronic device 1 further comprises one or more cooling means 37 that are mounted inside the housing 7 onto the back cover 11.
The electronic device 1 of the prior art has several drawbacks. First, the display housing 21 that serves as a necessary electromagnetic shielding between the electronics module 3 and the LCD layer 17 and the backlight layer 19 is relatively heavy and adds considerably to the weight of the device. However, it cannot just be left aside as some shielding between the display module 5 and the electronics module 3 is necessary. Furthermore, the display housing 21 considerably increases the thickness of the electronic device 1 which is disadvantageous if the electronic device 1 shall be used in environments in which space is limited.
In the specific application of an electronic device in an aircraft as a flight attendant panel or as a display for an in-flight entertainment system (IFE) the production is further complicated as the mounting of the display layer 17 and the backlight layer 19 in the display housing 21 have to be modified to fulfil civil aviation specifications. Furthermore, the size of the display housings 21 and the mounting holes 25 provided therein considerably varies among different manufacturers, so that different displays modules 5 cannot be mounted to the same electronics module 3. In consequence, a redesign of the printed circuit board 27 is necessary whenever the display module 5 shall be exchanged with a display module of a different type.